Those of you who sew, you know what this is. But, did you know that if you loose it and need another one, it's expensive? 
For some odd reason, this one didn't sit were it should be. I have two sewing machines: mums old one and my old slightly faulty one. As I was going to use mums I realised that the thing that holds the under tread spool (or what it's called in English...) was gone. I realised that when I was about to put the under tread spool in its place and found it, to my big surprise, to be empty . So, I switched machines and used my slightly erratic one. Then I thought I'd try my old machines thing in the functioning one... that didn't work at all. So, different 'holders' for different machines, which of course I should've figured out without testing!
I went online to see if I could buy a replacement, because I really need this sewing machine... And, yes... there're new ones, and used ones to buy... and they cost a small fortune! 50 Euro for a used one!! 100 Euro for a new one!! Even worse! So, I sat down and thought were on earth I could've thought it be a good place for it, outside the sewing machine. I saw a small pot with sewing stuff (I'd already gone through the large boxes with threads and other stuff...) and to my delight, there it was!! 
One problem less...